It looks like it could perhaps be possible to add multiple mirrors to vehicles at runtime.
The mirrors render (arbitrary ?) additional perspectives in real-time together with the main player camera.
It might be possible to exploit this to render multiple different views on the same screen (that of the player's camera). If mirrors were placed inside a vehicle's cabin and always faced the player's camera, d3dshot_screen_grabber would be able to publish them as individual image streams.